Arc suppressor



Nov. 28,, 1944. Q. MASENG 9 5 ARC SUPPRESSOR Filed March 23, 1942 HNVENTOR U2 511/ Ma 8872 ATTOR EY Patented Nov. 28, 1944 UNITED ARC SUPPRESSOR Olav Maseng, Detroit, Mich., assignor to Square D Company, Detroit, Micln, a corporation of Michigan Application March 23, 1942, Serial No. 435,799

7 Claims.

This invention relates to are suppressors for electric circuit breakers and has for its object the provision of a simple, inexpensive and effective arc suppressor for the interruption of arcs drawn between contacts of electrical circuit interrupters such as automatic electric circuit breakers.

Another object of the invention is the provision of an arc suppressor composed of superposed pairs of spaced insulating plates, with each pair formed to provide separate chambers through one of which the movable contact moves and with the chambers interconnected by a restricted passageway inclined to the longitudinal axis of the chambers.

*Another object of the invention is to provide an arc suppressor for an electric circuit breaker providing for restricted passage of arc gases against a plurality of projecting edges with provisions for substantially isolating a portion of the arc gases from the normal arc path.

Other objects and features of this invention will be readily apparent to those skilled in the art from the specification and appended drawing illustrating certain preferred embodiments in which:

Figure l is a vertical sectional view of an arc suppressor according to the present invention.

Figure 2 is a partial vertical sectional view on the line II-II of Figure 1.

Figure 3 is a horizontal sectional view on the line III-III of Figure l.

Figure 4 is a perspective view of the arc chamber liner with a portion of the transverse plates in place.

Figure 5 is a perspective view of one of the arc suppressor plates.

Figure 6 is a perspective view of the other are suppressor plate.

In the drawing, in which like reference numerals indicate like parts, a circuit breaker base is indicated generally at I having a cover 2 therefor. A conducting connector 3 mounted upon an end ledge of the circuit breaker base extends within the circuit breaker interior and there carries the circuit breaker contact 3 with which cooperates a movable contact 5 mounted upon the end of a switching arm 6. The are suppressor is disposed about and above the cooperating contacts 4 and 5, being disposed between a pair of insulating and sealing plates 1 and a pair of insulating plates 8 between the arc chamber and the interior of the breaker, the plates 8 being provided with elongated narrow slots 9 closely receiving the switching arm 6. The arc chamber liner is otherwise bounded by the walls II and I2 01 the breaker base.

The are chamber liner I3 is formed into U- shape from a sheet of insulating material and is provided with punched out slots shown in the bight I4 and side walls l5 and I6. Within the U-shaped chamber liner l3 are mounted the horizontally and vertically spaced insulating plates l1 and I8. These spaced plates are mounted within the liner through the end portions l9 and side lugs 2|, with the end portions I9 extending within the slots in the bight of the U and with the side lugs extending within and being interlocked with the slots in the side walls l5 and it of the liner by a longitudinal movement which securely holds the spaced plates in position preventing their removal, except in a longitudinal direction, which removal is prevented by the plates 9. The manner of holding and mounting the transverse plates within the liner is more particularly shown in the'sectional view of Figure 3 and the perspective view of Figure 4, Figure 4 showing the partial assembly of a few of the plates within the liner. The plates H are all mounted in one side wall 15 of the liner i3 and the plates M are all mounted in the other side wall it of the liner l3. The plates ill and 58 are spaced apart in the same horizontal plane as shown in Figures 2 and 3 and the individual plates El and G8 are spaced apart vertically as shown more particularly in Figures 1 and 2.

Within the horizontal plane in which the plates ii and it! are disposed, they form a large chamber 22 directly over the cooperating contacts l and ii, and a. second chamber 23 toward the bight i i of the liner it, the two chambers 22 and 23 being connected by a restricted portion 2% inclined to the longitudinal axis of the arc chamber by beginning at one corner of the chamber 22 and communicating with the opposite corner of the chamber 23, thus forming an offset and restricted path for the arc gases between chambers 22 and 23. This restricted, inclined communicating path 2 1 is formed by the projection 25 on the plate H and by the projection 29 on the plate l8, the projection 25 forming the boundary for the chamber 22 against which are gases impinge, the projection 26 being similarly interposed in a passage of arc gases between the chambers, thus forming the resultant restricted and inclined communication portion 24. It will, of course, be understood from the drawing that the foregoing chambers and communicating portion occur only within the and that the vertical spaces between these plates are entirely free and without obstruction in the entire space bounded by the side walls I5 and IS,-

the bight l4 and the plates 8.

A top for the arc chamber is provided by the iron or steel plate 21 mounted in opposed slots in the side walls l5, l6, but spaced from the bight H and the liner I3 to provide the small venting opening 28. The liner l3, plates l1 and I8, and plates 8 are preferably formed of a sheet like insulating material such as fiber or arc resisting Bakelite.

The arc suppressor, according to the present invention, provides a simple and inexpensive, but extremely efiicacious construction for the interruption of the relatively heavy arcing currents for electric circuit breakers, particularly of the type providing for manual operation and also for automatic opening of the circuit upon the occurrence of current overloads; for example, the arc suppressor has shown itself to effectively interrupt alternating currents of the order of 10,000 R. M. S. amperes in one cycle or less of a 60 cycle current, and at voltages of the order of 600 volts, although its efiectiveness is, of course, not limited to these particular values and these are cited solely for the purpose of showing the relatively heavy duty services in which the simple arc suppressor structure of this invention may be efiectively used.

While applicant does not desire to be restricted to any particular theory of operation of his arc suppressor, its efiectiveness may extend at least in part to the provision of the passageway for the arc gases between the chambers, restricted so as to impede their flow, but large enough so that effective flow is maintained with the opposite projections on the plate which form the passageway, presenting a plurality of edges immediately into the path of the arc gases and with the second group of chambers 23 acting to trap a considerable portion of the arc gases so as to isolate them from the main arc path and to tend to prevent reignition of the are after the current passes through its zero point. The how of gases from chamber 22 to chamber 23, which would normally be affected is enhanced by the position of the vent 28. The plates 21 appear to be efiective in attracting and condensing metal vapor generated in the arc.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims:

What is claimed is:

1. An arc suppressor for an electric circuit breaker having a stationary contact and a movable contact cooperating therewith, comprising a plurality of insulating plates disposed in pairs spaced on opposite sides of the path of movement of the movable contact with the plates in each pair having their planes aligned, and with the planes of the pairs spaced apart along the line of the path of movement of the movable contact, said plates having straight portions parallel to their longitudinal axes and portions projecting therefrom with abrupt and inclined edges, the inclined edge of one plane in each pair being disposed in parallel spaced relation to the inclined edge of the other plate of the pair to form a passageway and with the straight portions and the abrupt edges of the projections forming a pair of spaced chambers connected by the assageway between the inclined edges of the plates, the plates being disposed with the movable contact movable through one series of said chambers disposed in superposed relation.

2. An arc suppressor structure for an electric circuit breaker having a pair of separable contacts between which an arc is drawn upon separation during the passage of current therethrough, comprising a plurality of pairs of insulating plates spaced in parallel planes on opposite sides of the path of separation of said contacts, with the plates in said parallel planes disposed in superposed, spaced relation, the plates being shaped to form, in said planes, a series of unobstructed chambers over said contacts within which said are is initially formed and a second series of unobstructed chambers spaced from said first series of chambers and connected therewith by elongated, restricted passageways inclined to the longitudinal axis of the chambers, and a top plate of metallic material disposed out of the current path and parallel to said insulating plates above the open position of the movable contact for attracting and condensing metal vapor generated in the arc.

3. An arc suppressor for an electric circuit breaker having a stationary contact and a movable contact cooperating therewith, comprising a plurality of insulating plates disposed in pairs spaced on opposite sides of the path of movement of the movable contacts with the plates in each pair having their planes aligned, and with the planes of the pairs spaced apart along the line of the path of movement in the movable contact, said plates having straight portions parallel to their longitudinal axes and portions projecting therefrom with abrupt and inclined edges, the inclined edge of one plate in each pair being disposed in parallel spaced relation to the inclined edge of the other plate of the pair to form a passageway and with the straight portions and the abrupt edges of the plates forming a pair of spaced chambers connected by the passageway between the inclined edges of the plates, the plates being disposed with the movable contact movable through one series of said chambers disposed in superposed relation, and a top plate of metallic material disposed out of the current path and parallel to said insulating plates above the open position of the movable contact for attracting and condensin metal vapor generated in the arc.

4. An arc suppressor structure for an electric circuit breaker having a pair of separable contacts between which the arc is drawn on separation during the passage of current therethrough, comprising insulating plates disposed in substantially parallel planes spaced along the path of separation of the contacts, the spaces between the planes being unobstructed, the plates being formed to provide in each plane a pair of unobstructed chambers, the chambers in the plurality of planes being superposed with one of the group of chambers enclosing the path of separation of the contacts, the chambers in each of said planes being connected by restricted passageways of substantially uniform width.

5. An arc suppressor structure for an electric circuit breaker having a pair of separable contacts between which the arc is drawn on separation during the passage of current therethrough, comprising insulating plates disposed in substantially parallel planes spaced along the path 2,ses,eoe

of separation of the contacts, the spaces between the planes being unobstructed the plates being formed to provide in each plane a pair of unobstructed chambers, the chambers in the plurality of planes being superposed with one of the group of chambers enclosing the path of separation of the contacts, the chambers in each of said planes being connected by restricted passageways of substantially uniform width, the axes of said passageways being inclined to the axis of the arc suppressor structure and extending from corners of one group of chambers to the opposite corners of the other group of chambers.

6. An arc suppressor structure for an electric circuit breaker having a pair of separable contacts between which an arc is drawn upon separation during the passage of current therethrough, comprising a plurality of pairs of insulating plates spaced, in parallel planes, on opposite sides of the path of separation of the contacts, with said planes spaced along said path of separation, the plates in said parallel planes being disposed in superposed spaced relation, projections on said plates extending toward the axis of the arc suppressor structure, and inclined edges on said projections with the inclined edge of one plate of each pair being disposed in parallel spaced relation to the inclined edge on the other plate oi. each pair, the projections dividingthe space between each pair oi plates into two chambers joined by a restricted passageway of uniform width provided by the space between said inclined edges, one set 0! the superposed chambers enclosing the path of separation of said contacts.

'7. An arc suppressor structure for an electric circuit breaker having a pair 01' separable contacts between which an arc is drawn upon separation during the passage of current therethrough, comprising a plurality of pairs of insulating plates spaced, in parallel planes, on opposite sides of the path of separation of the contacts, with said planes spaced along said path of separation, the plates in said parallel planes being disposed in superposed spaced relation, projections on said plates extending toward the axis of the arc suppressor structure, and inclined edges on said projections with the inclined edge of one plate of each pair being disposed in parallel spaced relation to the inclined edge on the other plate of each pair, the projections dividing the space between each pair of plates into two chambers joined by a restricted passageway of uniform width provided by the space between said inclined edges, one set of the superposed chambers enclosing the path of separation of said contacts, said passageways permitting the flow of arc gases from the enclosing chambers into the chambers remote therefrom, but restricting the flow of arc gases in the reverse direction OLAV MASENG. 

